Electrodeposited Nano-Twins Copper Layer and Method of Fabricating the Same

ABSTRACT

An electrodeposited nano-twins copper layer, a method of fabricating the same, and a substrate comprising the same are disclosed. According to the present invention, at least 50% in volume of the electrodeposited nano-twins copper layer comprises plural grains adjacent to each other, wherein the said grains are made of stacked twins, the angle of the stacking directions of the nano-twins between one grain and the neighboring grain is between 0 to 20 degrees. The electrodeposited nano-twins copper layer of the present invention is highly reliable with excellent electro-migration resistance, hardness, and Young&#39;s modulus. Its manufacturing method is also fully compatible to semiconductor process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This present application relies on Taiwanese Patent Application No.100141898 filed on Nov. 16, 2011. The abovementioned foreign applicationis herein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for preparing electrodepositednano-twins copper layer and the nano-twins copper layer prepared by thesame, more particularly, to a method for preparing a nano-twins copperlayer having a plurality of [111] surfaces on its surface and thenano-twins copper layer thereof.

2. Description of Related Art

Mechanical strength of metallic material increases generally when thesize of the crystal grain is reduced to a nanoscale level. Somenano-scale levels of thin metal films can even have particularmechanical properties such—Young's coefficient. As a result, twins metalhaving nanoscale crystalline properties will be suitable forapplications of through silicon via, semiconductor chip interconnect,packaging substrate pin through hole, metal interconnect (for example,copper interconnect), or metal materials on substrate.

In terms of electrical performance of microelectronic devices,electromigration has become a critical reliability issue of Cu wires.From the disclosure of the past research, three methods have beendiscovered to increase the electromigration lifetime of the wires.

The first method is to fabricate the Cu grain structure with a [111]preferred orientation, so as to significantly enhance electro-migrationresistance, and reduce the possibility of formation of voids caused byelectro-migration.

The second method is to increase the grain size to decrease the area ofgrain boundary, and to further reduce the migration path of atoms. Thethird method is to add metals having nano-twins structure into thewires. The atoms move along the direction of the moving electrons andresult in electro-migration damage. Moreover, the electromigration ratecan be retarded at twin boundaries. In the spirit of this workingprinciple, nano-twins can inhibit the formation of voids in theinterconnect, and directly improve the lifetime of electrical devices.In other words, the higher the nano-twins density inside theinterconnect is, the better anti electro-migration will be.

Generally, nano-twins copper metal layer is prepared through physicalvapor phase deposition (PVD) or pulse electroplating. But the twinsmaterial prepared by these known technologies illustrated above can onlyobtain miniscaled and irregular nano-twins, and suffer high productioncost. In addition, PVD cannot fill Cu in trenches or vias with ahigh-aspect ratio. Hence, these known methods are not widely applied inmass production of semiconductor and electronic products. In otherwords, these methods still cannot be applied in industrial massproduction.

Several researchers disclosed the details of forming nano-twins coppermetal layers. For example, O. Anderoglu et al. disclosed a way forpreparing a nano-twins copper metal layer structure by physical vapordeposition (PVD). The thickness of a single crystal grain can reach onlyhundreds of nanometer, and only applicable for use in preparing seedlayers. (O. Anderoglu, A. Misra, H. Wong, and X. Zhang, Thermalstability of sputtered Cu films with nanoscale growth twins, Journal ofApplied Physics 103, 094322, 2008). In addition, because physical vaporphase deposition inherently cannot plate a concaved trough of a highaspect ratio well and deposition duration is long, neither structure norits preparative method is applicable for use in copper interconnects,through silicon via, or under-bump metallization (UBM), etc.

On the other hand, Xi Zhang et al. disclosed another way for producingnano-twins copper film through copper sulfate solution, and pulseelectrodeposition device. One drawback of the known technology comesfrom the fact that the size of produced crystal grains is too small, thetwins copper growth orientation cannot be controlled, and the pulsedelectrodeposition rate is low. Hence, its economic benefits downgrade.(Xi Zhang, K. N. Tu, Zhang Chen, Y. K. Tan, C. C. Wong, S. G.Mhaisalkar, X. M. Li, C. H. Tung, and C. K. Cheng. Pulse Electroplatingof Copper Film: A Study of Process and Microstructure, Journal ofNanoscience and Nanotechnology, VOL 8, 2568-2574, 2008).

U.S. Pat. No. 6,670,639B1 discloses a copper interconnection, wherein50% of the crystal grains of the copper or copper alloy inside theinterconnect are arranged in a uniform [111] crystal orientation, andconnects with crystal grains of other crystal orientation to form abamboo structure, and to form double crystal lattice on the wiresurface. The efficacy of the structure illustrated is to increase highreliability and to lower production cost. However, although the priorart can offer high reliability and low production cost, it cannot offerthe anti electro-migration as present with nano-twins at the same time.

U.S. Pat. No. 7,736,448B2 discloses a preparative method fortwins-copper interconnect using “pulsed electrodeposition”. The densityof the twins layer prepared thereof is high, but the crystal grain sizeis merely 300 nm-1000 nm, which are random, orderless small sizeisometric crystal grains. Furthermore, the range of operation for theelectric current density of the disclosed pulse electrodeposition in thesaid technology is limited to be within 4 mA/cm²-10 mA/cm², and the filmplating deposition rate is overly slow. Therefore, the materials'economic value is deprived by the shortcoming illustrated above.

In summary, there are generally two drawbacks with the prior arts: (1)the grain orientation therein is difficult to master. Only copper grainswith random orientations can be fabricated, and its effect on improvingproduct efficacy is limited when used in interconnect or contact points;(2) prior arts' deposition speed is low despite of use of pulse platingor physical vapor phase deposition. Its deposition duration is long,efficacy is low, and production cost is high. In other words, it cannotcompete against other products with respect to large-scale production.

Accordingly, the microelectronics industry needs a nano-twins coppermetal layer having a [111] preferred orientation, so as to come up withthe most favorable anti electro-migration for wires. At the same time,there is a need for nano-twins copper metal materials having excellentmechanical property, and the preparative method is also fast, and lowcost. Moreover, the preparative method is compatible with currentsemiconductor manufacturing, which is believed to be in line forreplacing directly the applicability value of the traditionalinterconnect or contact materials.

SUMMARY OF THE INVENTION

One main object of the present invention is to provide anelectrodeposited nano-twins copper metal layer and a preparative methodthereof. The nano-twins copper metal layer herein has improved antielectro-migration, hardness, and Young's coefficient. These improvedproperties are ideal for significantly enhancing the electromigrationreliability for electronic products, keeping down production cost, andmaking the material and the production thereof compatible with modernsemiconductor manufacturing.

In the electrodeposited nano-twins copper metal layer of the presentinvention, over 50% of a volume of the nano-twins copper metal layercomprises a plurality of crystal grains, wherein each of the pluralityof crystal grains is connected with one another, and each crystal grainis formed as a result of the plurality of nano-twins working to stack inthe direction of the [111] crystal axis, for which an angle includedbetween neighboring crystal grains is 0° to 20° in a stacking direction,more preferably 0° to 10°, and most preferably 0°.

The electrodeposited nano-twins copper metal layer of the presentinvention features a structure completely different from the commonlyknown arts. In particular, the nano-twins copper metal has grains havingsubstantially preferred direction in [111] and in the meantime highlydense nano-twins. The thickness of the electrodeposited film can evenreach approximately above 20 micrometers (even above hundreds ofmicrometers). The density of the nano-twins in the whole metal materialsurpasses those produced by commonly known arts, and can possessoutstanding anti electro-migration and mechanical characteristics. Inother words, the electrodeposited nano-twins copper metal layer of thepresent invention is suitable for mass production.

The present invention uses electrodeposition as a means to producenano-twins copper metal layer having a preferred direction. Thenano-twins copper metal layer of the present invention has at least 50%of surface area being [111] surface, meaning that a [111] surface isexposed on over 50% of surface area. Furthermore, an angle includedbetween the direction of crystal axis [111] of the grains and its growthdirection is within 20°, and it is preferred that the grain hasessentially the same direction of [111].

In the present invention, the thickness of electrodeposited nano-twinscopper metal layer can vary according to the direction ofelectrodeposition, for which it is preferred to be approximately 0.1 μm,making it only applicable for use as seed layer, and not capable formore straight forward application as in wires. The thickness ofelectrodeposited nano-twins copper metal layer, on the other hand, canbe 0.1 μm-500 μm, and its industrial application can therefore be verydiverse (for example, through silicon via, semiconductor chipinterconnect, pin through hole, or metal interconnect).

As shown in the three-dimensional perspective diagrams of thecross-sectional diagram of FIG. 2A and FIG. 2B, the electrodepositednano-twins copper metal layer 14 of the present invention comprisesconsiderable number of crystal grains 16, and each crystal grain hasplural layer-shaped nano-twins copper (for example, neighboring sets ofblack lines and white lines constitute a twins copper), therefore, thewhole nano-twins copper metal layer of the present invention comprises agreat number of nano-twins copper. The nano-twins copper of the presentinvention are stacked in order on the basis of a [111] surface, andforming a crystal grain 16 having a preferred direction.

In the present invention, more preferably, at least 50% of crystalgrains have a longitudinal axis, the longitudinal axis; the longitudinalaxis would show the direction of stacking/growth (or long axis). At thesame time, the twins copper metal layer has thickness direction, and thethickness direction is perpendicular to a surface of the twins coppermetal layer. An angle included between the [111] crystal axis of thecrystal grain and the longitudinal axis is 0 to 20°, and it is preferredthat the longitudinal axis direction of the crystal grain is essentiallyidentical to the twins metal layer's thickness direction.

In the above mentioned electrodeposited nano-twins copper metal layer,it is preferred that at least 90% of surface of the nano-twins coppermetal layer is [111] surface; it is more preferred that at least 100% ofsurface of the nano-twins copper metal layer is [111] surface, meaningthat all surfaces exposed in nano-twins copper metal layer is [111]surface.

Furthermore, in the electrodeposited nano-twins copper metal layer ofthe present invention, it is more preferred that at least 70% of thecrystal grains is formed as a result of the stacking of pluralnano-twins; it is much more preferred that at least 90% of the crystalgrains is formed as a result of the stacking of plural nano-twins.

In the present invention, the electrodeposited nano-twins copper metallayer is preferred to further include a seed layer, which takes up1%-50% of the volume of the nano-twins copper metal layer, for which itis preferred to be 1%-40% of the volume, it is more preferred to be1%-30% of the volume, and even more preferred to be 1%-10% of thevolume. Because at the start of electrodeposition, a bit of seed layerwill extend to cover the substrate's surface, therefore there willlikely be a bit of seed layer not composed of twins copper on the bottomportion of the nano-twins copper metal layer that is formed accordingly.

Similarly, it would follow that the existence of a seed layer can beused as one of the determining conditions for calling whether anelectrodeposition was used as a means of production. For example, a seedlayer would not be put to use if the metal layer was produced bysputtering, and no impure elements would exist in the elementalanalysis. However, such means of production suffers from drawbacksincluding slow speed rate, high equipment cost, therefore it is lesslikely to be used in large-scale production setting. Furthermore, ifthere was any disturbance during the electrodeposition process, suchcomplexity could lead to partly impure crystal grains in between crystalgrains, wherein the impure grain would include impure elements inaddition to copper (including oxygen, sulfur, carbon, phosphorus, etc.).In this case, the crystal grain is not formed as a result of thestacking of nano-twins copper; or the angle included between thestacking direction of the nano-twins in the impure crystal grains andthe [111] crystal axis is greater than 20°.

In the electrodeposited nano-twins copper metal layer of the presentinvention, the crystal grain has a diameter preferably of 0.1 μm-50 μm,more preferably 1 μm-10 μm. The thickness of the crystal grain ispreferred to be 0.01 μm-500 μm, and more preferably 0.1 μm-200 μm.

In addition, the electrodeposited nano-twins copper metal layer of thepresent invention has excellent mechanical property andelectro-migration characteristics, which can be applied in theproduction of through silicon via, semiconductor chip interconnect,packaging substrate pin through hole, various metal interconnect, orsubstrate circuit, of three-dimensional integrated circuit (3D-IC),which can find great use in technological applications for integratedcircuit industry.

Another object of the present invention is to provide a method forpreparing the nano-twins copper metal layer, which useselectrodeposition to produce a nano-twins metal layer of a thickness ofsubmicron to over tens of microns, and can moderate the crystallographicordering arrangement or the nano-twins metal layer, to make a highlyordered [111] plane substantially normal to the growth direction.

The method for preparing nano-twins copper metal layer of the presentinvention comprises the following steps:

-   -   (A) providing an electrodepositing device, wherein the        electrodepositing device comprises an anode, a cathode, a        plating solution, and an electrical power supply source, and the        electrical power supply source is connected with the cathode on        one end, and connected to the anode on the other end; and    -   (B) using the electrical power supply source to provide        electrical power to carry out electrodepositing, with a surface        of the anode used for growing nano-twins copper metal layer;        wherein over 50% of a volume of the nano-twins copper metal        layer comprise s a plurality of crystal grains, each of the        plurality of crystal grain is connected with one another, and        each crystal grain is formed as a result of the plurality of        nano-twins working to stack in the direction of the [111]        crystal axis, for which an angle included between neighboring        crystal grains is 0 to 20° in a stacking direction, and the        plating solution comprises: a copper-based salinized substrate,        an acid, and chloride anion supply source.

The electrodeposited nano-twins metal layer of the present inventionfeatures a structure completely different from the commonly known arts.In particular, the electrodeposited nano-twins metal layer has crystalgrains having substantially preferred orientation in [111] and in themeantime highly dense nano-twins, the thickness of the crystal grain canreach approximately above 20 micrometers (even above hundreds ofmicrometers), the density of the nano-twins in the whole metal materialsurpasses these produced by commonly known arts, and make foroutstanding anti electro-migration and mechanical characteristics, andaltogether make for practical sizes required in various electronicparts, showing worth for mass production.

The present invention uses electrodeposition to produce nano-twinscopper metal layer having a preferred direction, the nano-twins coppermetal layer at least has 50% of surface as [111] surface, meaning that a[111] surface of a nano-twins is exposed on over 50% of surface of anano-twins copper metal layer. In addition, the angle included betweenthe crystal axis [111] direction of the crystal grain and growthdirection (that is, nano-twins stacking direction) is within 20°, and itis preferred that the crystal grain has substantially identical [111]direction.

For the plating solution mentioned above, one of the primary functionsof the chloride anion is to fine-tune the growth direction of crystalrains, and to therefore equip twins with preferred crystallizationorientation. Furthermore, the acid can be an organic acid or inorganicacid, for increasing electrolyte concentration to improve rate ofelectrodeposition, for which choice of use for the acid can be sulfuricacid, methyl sulfonate, or a combination thereof.

Furthermore, the acid concentration in the plating solution is preferredto be 80-120 g/L. Even more, the plating solution should at the sametime include copper ion source (that is, copper salts, for example,copper sulfate or methyl sulfonic copper). In a preferred composition ofthe plating solution, and additives can be further included, which canbe selected from a group consisting of gelatin, surfactant, latticemodification agent, and a combination thereof, to adjust the growthorientation of the crystal grain that can be fine-tuned by the additivesubstances.

In the method for preparing twins metal layer of the present invention,the electrical power source is preferred to be a direct currentelectrodeposition supply source, or high-speed pulse electrodepositionsupply source, or direct current elecrodeposition and high-speed pulseelectrodeposition interchangeably, for enhancing twins metal layerformation rate. When direct current electrodeposition is used in thestep (B), the electric current is preferred to be 10 mA/cm²-120 mA/cm²,most preferred to be 20-100 mA/cm² (for example, 80 mA/cm²). Whenhigh-speed pulse electrodeposition supply source is used in the step(B), the operation conditions are preferred to be: T_(on)/T_(off) (sec)at 0.1/2-0.1/0.5 (for example, 0.1/2, 0.1/1, or 0.1/0.5), electriccurrent at 10-250 mA/cm² (most preferably 50 mA/cm²). The growth rate ofthe nano-twins copper is measured by actual conduction time when itundergoes electrodeposition running the above conditions, which, in apreferred setting, is 0.22 μm/min-2.64 μm/min. For example, when theelectric current for electrodeposition is 80 mA/cm² in step (B), thetwins metal growth rate can be between 1.5 μm/min-2 μm/min (for example,1.76 μm/min). In the present invention, the thickness of the nano-twinscopper metal layer can be adjusted according to electrodepositionduration, with the range of the thickness being preferred to be about0.1 μm-500 μm, more preferred to be 0.8 μm-200 μm, and even morepreferred to be 1 μm-20 μm. Compared to the present invention, the twinscopper metal layer prepared from generally known technology can only beused as a seed layer because it has no via filling capability, has apreferred orientation, and the mass production thickness can merely beabout 0.1 μm. Therefore the known prior arts can only be used as seedlayer, and cannot be directly used as interconnect. But the thickness ofthe electrodeposited nano-twins copper metal layer of the presentinvention can be 0.1 μm-500 μm, therefore its applicability is verydiverse (for example, through silicon via, semiconductor chipinterconnect, packaging substrate pin through hole, or metalinterconnect). In addition, when the electrodeposition is underway, thecathode or the plating solution can be spun at a rotational speed of 50to 1500 rpm, so as to help twins growth orientation and speed rate.

In the method for preparing twins metal layer of the present invention,the cathode is preferred to be a substrate having seed layer on asurface, or a metal substrate (for example, copper tinsel substrate, orsubstrate having copper tinsel on a surface). For example, the substratecan be selected from a group consisting of: silicon substrate, glasssubstrate, quartz substrate, metal substrate, plastic substrate, printedcircuit board, copper tinsel substrate, III-V group material substrate,and a combination thereof. When electrodeposition is underway, thecathode and the plating solution are preferred to be spun at arotational rate of 50 to 1500 rpm, so as to help columnar crystal grainsgrow.

The crystal grain obtained by the method for preparing nano-twins coppermetal layer of the present invention has a diameter preferably of 0.1μm-50 μm, more preferably 1 μm-10 μm; the crystal grain has a thicknesspreferably of 0.01 μm-500 μm, more preferably 0.1 μm-200 μm.

The nano-twins copper metal layer prepared by the method of the presentinvention has excellent mechanical property and electro-migration, canbe used in the preparation of through silicon via, packaging substratepin through hole, various electrical interconnect, or substrate circuitand others for three-dimensional integrated circuit (3D-IC). These canfind great use in the technological application for integrated circuitindustry.

In addition, the present invention further provides a substrate havingnano-twins copper metal layer, comprising: a substrate; and the abovementioned nano-twins copper metal layer, which is disposed on a surfaceor interior of the substrate. Wherein, the substrate is selected from agroup consisting of silicon substrate, glass substrate, quartzsubstrate, metal substrate, plastic substrate, printed circuit board,III-V group material substrate, and a combination thereof.

The substrate having the nano-twins copper metal layer of the presentinvention can comprise packaging substrate having wire layer,three-dimensional integrated circuit (3D-IC) board and others. That is,in the substrate having the nano-twins copper metal layer of the presentinvention, the nano-twins copper metal layer can be used a s throughsilicon via, pin through hole, any metal interconnect, or substratecircuit, and others.

The method for preparing twins metal of the present invention takessignificantly shorter time than the generally known physical phasedeposition method or pulse electrodeposition, has faster deposition rateand speed, making call for expensive vapor phase deposition deviceunnecessary, therefore production cost can be significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an electrodepositing device according toExample 1 and 2 of the present invention;

FIG. 2A shows a cross-sectional focused ion beam (FIB) photo of anano-twins copper metal layer according to Example 1 of the presentinvention;

FIG. 2B is an isometric representation of a nano-twins copper metallayer according to Example 1 of the present invention;

FIG. 3 is an exemplary display of X-ray analysis result from a plan-viewfor a columnar crystal of nano-twins copper metal layer according toExample 1 of the present invention;

FIG. 4 is an exemplary display of EBSD pattern for a columnar crystal ofnano-twins copper metal layer according to Example 1 of the presentinvention;

FIG. 5 shows a statistical analysis result for a crystal of nano-twinscopper metal layer of FIG. 4 deviating from an angle to positive [111]direction according to Example 1 of the present invention.

FIG. 6 is a cross-sectional focused ion beam (FIB) photo of a nano-twinscopper metal layer prepared by direct current electroplating at 20mA/cm² according to Example 1 of the present invention.

FIG. 7 is a cross-sectional focused ion beam (FIB) photo of a nano-twinscopper metal layer prepared by direct current electroplating at 40mA/cm² according to Example 1 of the present invention;

FIG. 8 is a cross-sectional focused ion beam (FIB) photo of a nano-twinscopper metal layer prepared by direct current electroplating at 100mA/cm² according to Example 1 of the present invention;

FIG. 9 is a cross-sectional focused ion beam (FIB) photo of a nano-twinscopper metal layer prepared by direct current electroplating at 50mA/cm² according to Example 2 of the present invention;

FIG. 10 shows a result of X-ray analysis from a plan view for a crystalgrain of a nano-twins copper metal layer prepared by pulseelectrodepositing according to Example 2 of the present invention;

FIG. 11 is a perspective view showing a wire substrate according toExample 4 of the present invention;

FIG. 12 is a display and graph of elemental analysis according totesting example of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereafter, examples will be provided to illustrate the embodiments ofthe present invention. Other advantages and effects of the inventionwill become more apparent from the disclosure of the present invention.Other various aspects also may be practiced or applied in the invention,and various modifications and variations can be made without departingfrom the spirit of the invention based on various concepts andapplications.

The figures presented herein are simplified diagrams showing examples ofthe current invention. It must be understood that the figures are onlyillustrative of the associated elements of the current invention, andare not intended to be the actual embodiments. The number, shape andother dimensions of the elements in the actual embodiments are chosenfor specific design purposes, and their configuration and pattern may bemore detailed.

Example 1

An electrodepositing device 1 as shown in FIG. 1 is provided, theelectrodepositing device 1 comprises an anode 11, a cathode 12, whichare immersed in the plating solution 13 and are each connected to adirect current electrical power supply source 15 (Keithley 2400 is usedherein). In the present case, the anode 11 is made from a materialincluding metal copper, phosphorus copper or inert anode (for example,titanium-plated platinum); cathode 12 is made from a material includingsilicon substrate having its surface plated by copper seed layer, andcan be made from a material selected from a group consisting of glasssubstrate having its surface plated by conductive layer and seed layer,conductive layer and seed layer plated surface glass substrate, quartzsubstrate, metal substrate, plastic substrate, or printed circuit boardetc. The plating solution 13 comprises copper sulfate (copper ionconcentration being 20-60 g/L), chloride anion (concentration being10-100 ppm), and methyl sulfonate (concentration being 80-120 g/L), andother surfactant or lattice modification agent (such as BASF Lugalvan1-100 ml/L) can be added. The plating solution 13 of the present examplecan further comprises organic acid (for example, methyl sulfonate), orgelatin etc., or a combination thereof for adjusting crystal graincomposition and size.

Next, a direct current having a 20-100 mA/cm² electric current is usedin electrodeposition, in which nano-twins are grown from the cathode 12in the direction pointed by the arrow as shown in FIG. 1. A rotationalspeed of about 50 to 1500 rpm is applied on silicon chip or solution.During the growth process, the [111] surface of the twins and the planarsurface of the nano-twins copper metal layer are roughly perpendicularlyto the electric field orientation, and the twins copper is grown atabout 1.76 μm/min. The fully grown nano-twins copper metal layercomprises a plurality of crystal grains, wherein the crystal grins areformed by a plurality of twins copper. Since the nano-twins extend toreach the surface, [111] surface is still exposed on the surface. Thethickness of the twins copper 14 achieved from electrodeposition isapproximately 20 μm. [111] crystal axis is an axis normal to the [111]surface.

FIG. 2A is a cross-sectional focused ion beam (FIB) photo of the twinscopper prepared with 80 mA/cm² of the present example according to thecurrent example, and FIG. 2B is an isometric representation of thenano-twins copper layer of the present example. According to FIGS. 2Aand 2B, over 50% of volume of the nano-twins copper layer 14 prepared inthe current example comprises a plurality of columnar crystal grains 16,and each crystal grain has a plurality of layer-shaped nano-twins copper(for example, neighboring black line and white line constitute a twinscopper, and are stacked in a stacking direction 19 to form crystalgrains 16), therefore, the whole nano-twins copper metal layer of thepresent invention comprises a significant number of nano-twins copper.The diameter D of these columnar crystal grains 16 can range from about0.5 μm to 8 μm and the height L can range from about 2 μm to 20 μm,nano-twins plane 161 (level striation) and the [111] planar surface areparallel to each other, crystalline grain boundary 162 can be foundbetween twins crystals, the [111] plane surface of copper isperpendicularly to the T direction of thickness, and the thickness T ofthe twins copper layer 14 is about 20 μm. The angle included betweenstacking direction of neighboring crystals (which are almost identicalto [111] crystal axis) ranges between 0° and 20°.

In the present embodiment, the thickness T of the twins copper layer 14can be adjusted based on electrodeposition duration, which ranges about0.1 μm-500 μm.

As shown in FIG. 3, a result from X-ray analysis for a plan-view ofnano-twins copper metal layer according to the present example is shown.X-ray is incidentally shot through the electrodeposited copper surface.As will be seen in FIG. 3, the electrodeposited layer crystal grain hasa preferred orientation of [111] crystal axis (as shown by Cu(III) inFIG. 3). The Si(004) in the drawing is the diffraction peak of thesilicon substrate. Other planar diffraction peaks of copper are notpresent, indicating that the copper prepared by the present example has[111] crystal axis.

FIG. 4 shows the result of using electron backscatter diffraction (EBSD)as a means of analyzing the surface crystal orientation, which showsthat all surface crystal grain orientation are centered around [111]orientation, which is the color blue. FIG. 5 shows the statistical studyresult for these crystal grains deviating from [111] orientation angle,it can be seen that the percentage of crystal grains whose angledeviating from the [111] orientation by within 10° (<10)° is over 90%.

Furthermore, the nano-twins copper metal layer having [111] preferredorientation of the present invention can also be obtained from otherelectric current density condition, as shown in the cross-sectional FIGphotos of FIGS. 6-8, where the electric currents are each 20 mA/cm², 40mA/cm², and 100 mA/cm², it can also be seen in the diagram that thetwins copper obtained by other electric current also has [111] preferredorientation.

As seen in FIG. 6, FIG. 7, or FIG. 8, in the present invention, impurecrystal grains 17 can be found between columnar crystal grains 16, and asurface of the nano-twins copper metal layer has some seed layers 18.The reason for such establishment is that the substrate surface would becovered by some seed layers 18 at the start of electrodeposition,therefore some seed layers 18 not composed by twins copper can be foundon the formed nano-twins copper metal layer. Therefore, the nano-twinscopper metal layer of the present invention is defined to have acharacteristics of “over 50% of volume comprises a plurality of crystalgrains, each of the crystal grain is formed by the stacking of aplurality of nano-twins along [111] crystal axis orientation.”

Example 2

The combination of electrodepositing device and plating solution of thepresent example is the same as in Example 1, but pulse electrodepositionis used for plating instead of direct current power supply source.Silicon chip or solution is subject to rotation at a rate of about 0 to1500 rpm. T_(on)/T_(off) is kept below 0.1/0.5 (sec), electric currentdensity is kept at 50 mA/cm², and twins copper is grown (plating 6000cycles) from cathode moving toward the direction pointed by the arrow(as shown in FIG. 1). [111] plane of the twins is perpendicular to theorientation of electric field, and twins copper is grown at a rate of0.183 μm/min. The fully grown twins copper comprises a plurality ofcolumnar crystal grains; the columnar crystal grain has a plurality oflayer-shaped nano-twins copper, and the thickness of the nano-twinscopper layer obtained after electrodeposition is about 10 μm.

FIG. 9 is a cross-sectional focused ion beam (FIB) photo of thenano-twins copper metal layer prepared in the current example. As shownin FIG. 9, over 50% of volume of the nano-twins copper metal layerprepared in the current example comprises a plurality of crystal grains,the diameter D of the crystal grain ranges from about 0.5 μm to 8 μm,the level striation is the nano-twins layer (for example, neighboringsets of black lines and white lines constitute a twins copper), the[111] plane of copper and twins plane are substantially cover 50%perpendicular to the orientation of thickness T, and the thickness T ofcrystal grain is about 10 μm.

Furthermore, as shown in FIG. 10, a result diagram displaying X-rayanalysis of the nano-twins copper layer prepared by the present exampleis provided. The result shows that the nano-twins copper layer preparedby electrodeposition of the current example has a favorable [111]preferred orientation for which the intensity of diffraction of 280,000counts is higher than the diffraction peak of the silicon chip, and forhigher than Cu(222) diffraction peak, indicating that the twins copperlayer prepared by the current example has a more favorable [111]preferred direction than that done by direct current.

Example 3

The plating solution and method of the present example is the same asExample 1, but is different in an aspect that the current example haswire channel prepared by a semiconductor manufacturing process on thesubstrate surface, the micro through holes of the aspect ratio of 1:3,and that the nano-twins copper metal layer uses electrodeposition tofill holes and in turn forms interconnect.

Example 4

As shown in FIG. 11, a circuit substrate is provided, which includes thesame nano-twins copper metal layer prepared in Example 3. In otherwords, the nano-twins copper metal layer of the present example can beused in wires 3, and/or conductive throughhole 5. In addition, it canalso be used in the three-dimensional integrated circuit, etc.

And with regards to substrate material, the substrate can be siliconsubstrate, glass substrate, quartz substrate, metal substrate, printedcircuit board, or III-V group material substrate.

Testing Example

As shown in FIG. 12, an elemental analysis is conducted based on thenano-twins copper metal layer as prepared in Example 1. Testingconditions are shown in Table 1 below. By reference to the currentfigure, it can be observed that the nano-twins copper metal layerprepared from the electrodepositing method of the present inventionwould comprise a handful of impure grains, where these impure grainswould include impure elements in addition to copper (for example,oxygen, sulfur, carbon, phosphorous, and others). However, thenano-twins copper metal layer would be devoid of these impure elementsin the case of manufacture by sputtering.

TABLE 1 Sample Parameter Analytical Parameter Sputtering ParameterSample: 80 mA/cm² PI: Ga PI: Cs Polarity: Negative Energy: 25 KeVEnergy: 2KeV Charge current: 1.00 Charge current: 45.00 pA pA Area: 65.4× 65.4 μm² Area: 250.1 × 250.11 μm²

What is claimed is:
 1. An electrodeposited nano-twins copper metallayer, wherein over 50% of a volume of the nano-twins copper metal layercomprises a plurality of crystal grains, each of the plurality ofcrystal grain is connected with one another, and each crystal grain isformed as a result of the plurality of nano-twins working to stack inthe orientation of the [111] crystal axis, for which an angle includedbetween neighboring crystal grains is 0° to 20°.
 2. The electrodepositednano-twins copper metal layer according to claim 1, wherein thenano-twins copper metal layer further comprises a seed layer, whichtakes up 1% to 50% of the volume of the nano-twins copper metal layer.3. The electrodeposited nano-twins copper metal layer according to claim1, wherein a [111] surface of the nano-twins is exposed on over 50% of asurface of the nano-twins copper metal layer.
 4. The electrodepositednano-twins copper metal layers according to claim 1, wherein a thicknessof the nano-twins copper metal layer is 0.1 μm-500 μm.
 5. Theelectrodeposited nano-twins copper metal layer according to claim 4,wherein the thickness of the nano-twins copper metal layer is 0.8 μm-200μm.
 6. The electrodeposited nano-twins copper metal layer according toclaim 1, wherein at least 50% of the crystal grains has a longitudinalaxis, for which the longitudinal axis denotes the stacking direction fornano-twins, the twins copper metal layer has a thickness direction, forwhich the thickness direction is normal to a surface of the twins coppermetal layer, an angle included between the [111] crystal axis and thelongitudinal axis is 0° to 20°, and a longitudinal axis direction of thecrystal grain is essentially the same as the thickness direction of thetwins metal layer.
 7. The electrodeposited nano-twins copper metal layeraccording to claim 1, wherein at least 90% of a surface of thenano-twins copper layer is [111] surface.
 8. The electrodepositednano-twins copper metal layer according to claim 1, wherein all surfacesof the nano-twins copper metal layer are [111] surface.
 9. Theelectrodeposited nano-twins copper metal layer according to claim 1,wherein at least 70% of the crystal grains is formed as a result ofstacking of the plurality of nano-twins.
 10. The electrodepositednano-twins copper metal layer according to claim 1, wherein the crystalgrains further includes in between themselves impure crystal grains. 11.The electrodeposited nano-twins copper metal layer according to claim 1,wherein the crystal grain has a diameter of 0.01 μm-500 μm, and thethickness of the crystal grain is in a range of 0.01 μm-500 μm.
 12. Theelectrodeposited nano-twins copper metal layer according to claim 1,wherein the crystal grain has a diameter of 1 μm-10 μm, and thethickness of the crystal grain is in a range of 0.1 μm-200 μm.
 13. Theelectrodeposited nano-twins copper metal layer according to claim 1,wherein the nano-twins copper metal layer is used in through silicon via(TSV), semiconductor chip interconnect, packaging substrate pin throughhole, metal interconnect, or substrate circuit.
 14. A method forpreparing a nano-twins copper metal layer, comprising: (A) providing anelectrodepositing device, wherein the electrodepositing device comprisesan anode, a cathode, a plating solution, and an electrical power supplysource, and the electrical power supply source is connected with thecathode on one end, and connected to the anode on the other end; and (B)using the electrical power supply source to provide electrical power tocarry out electrodepositing, with a surface of the anode used forgrowing a nano-twins copper metal layer; wherein over 50% of a volume ofthe nano-twins copper metal layer comprises a plurality of crystalgrains, each of the plurality of crystal grain is connected with oneanother, and each crystal grain is formed as a result of the pluralityof nano-twins working to stack in the direction of the [111] crystalaxis, for which an angle included between neighboring crystal grains is0° to 20° in stacking direction, and the plating solution comprises: acopper-based salinized substrate, an acid, and chloride anion supplysource.
 15. The method for preparing a nano-twins copper metal layeraccording to claim 14, wherein a [111] surface of the nano-twins isexposed on over 50% of a surface area of the nano-twins copper metallayer.
 16. The method for preparing a nano-twins copper metal layeraccording to claim 14, wherein the crystal grain has a diameter of 0.01μm-500 μm, and the thickness of the crystal grain is in a range of 0.01μm-500 μm.
 17. The method for preparing a nano-twins copper metal layeraccording to claim 14, wherein the crystal grain has a diameter of 1μm-10 μm, and, and the thickness of the crystal grain is in a range of0.1 μm-200 μm.
 18. The method for preparing a nano-twins copper metallayer according to claim 14, wherein the plating solution furthercomprises a substance selected from a group consisting of gelatin,surfactant, lattice dressing agent, and a combination thereof.
 19. Themethod for preparing a nano-twins copper metal layer according to claim14, wherein the acid in the plating solution is sulfuric acid, methylsulfonate, or a combination thereof.
 20. The method for preparing anano-twins copper metal layer according to claim 14, wherein theconcentration of acid in the plating solution is 80-120 g/L.
 21. Themethod for preparing a nano-twins copper metal layer according to claim14, wherein in step (B) the current density for electrodeposition is10-120 mA/cm².
 22. The method for preparing a nano-twins copper metallayer according to claim 14, wherein the growth rate of the nano-twinscopper metal layer is 0.22 μm/min-2.64 μm/min.
 23. The method forpreparing a nano-twins copper metal layer according to claim 14, whereinin step (B) the growth rate of the twins metal is 1.5 μm/min-2 μm/minwhen the current density for electroplating is 80 mA/cm².
 24. The methodfor preparing a nano-twins copper metal layer according to claim 14,wherein in step (B) electrodeposition is carried out by direct currentelectrodeposition, high-speed pulse electrodeposition, or bothinterchangeably.
 25. The method preparing for a nano-twins copper metallayer according to claim 14, wherein the preparative method for thetwins copper metal layer is used in through silicon via (TSV),semiconductor chip interconnect, packaging substrate pin through hole,metal wire, or substrate circuit.
 26. The method for preparing anano-twins copper metal layer according to claim 14, wherein the cathodeis a substrate having a surface of a seed layer, or a metal substrate.27. The method for preparing a nano-twins copper metal layer accordingto claim 26, wherein the substrate is selected from a group consistingof: silicon substrate, glass substrate, quartz substrate, plasticsubstrate, printed circuit board, III-V group material substrate, and acombination thereof.
 28. The method for preparing a nano-twins coppermetal layer according to claim 14, wherein in step (B) when theelectrodeposition is underway, the anode or the plating solution arespun at a rotational speed of 50 to 1500 rpm.
 29. A substrate havingnano-twins copper metal layer, comprising: a substrate; and a nano-twinscopper metal layer according to claim 1, which is arranged inside, or onthe surface of the substrate.
 30. The substrate having nano-twins coppermetal layer according to claim 29, wherein the substrate is selectedfrom a group consisting of silicon substrate, glass substrate, quartzsubstrate, metal substrate, plastic substrate, printed circuitsubstrate, III-V group material substrate, and a combination thereof.